Strong gravitational lensing in the radio domain

PhD ceremony: mw. A. Berciano Alba, 14.45 uur, Academiegebouw, Broerstraat 5, Groningen

Thesis: Strong gravitational lensing in the radio domain

Promotor(s): prof.dr. L.V.E. Koopmans, prof.dr. M.A. Garrett, prof.dr. A.G. de Bruijn

Faculty: Mathematics and Natural Sciences

 

In the Universe, massive objects like galaxies and galaxy clusters behave as giant magnifying glasses that can provide multiple enlarged and distorted images of a single background source. This phenomenon is called strong gravitational lensing, and in some extreme cases can produce bright elongated images known as giant arcs. In this thesis, we illustrate three different applications of this phenomenon in the context of radio astronomy: (i) the study of a galaxy that is acting as a lens, (ii) the study of the internal structure of a source that is multiply imaged, and (iii) a statistical study of giant arcs produced by galaxy clusters. The first case of study is the system B1600+434, in which a galaxy is producing two images of the compact central region of another background galaxy. Our radio observations have confirmed that the brightness of one of the two images changes continuously over a period of four years due to the structure of the galaxy lens. The second case of study is an extended source observed at sub-mm wavelengths, which seems to be magnified by a galaxy cluster. Radio observations of this system support the hypothesis that part of the sub-mm emission is due to the collision of three very distant galaxies. Finally, we present the first predictions of the expected number of observable giant arcs at radio and sub-mm wavelengths by modeling the structure and evolution of galaxy clusters in detail. The future prospects for the study of multiply-imaged sources is also discussed.